The major goal of this program-project is to apply the skills of a multidisciplinary group of investigators to study the effects of stress on the aging process as well as the influence of age on ability to cope and adapt to different kinds of applied stress. As a working hypothesis, the participants of this program-project are exploring the possibility that it is the brain-endocrine relationship that is a critical focal point for the aging process. The conceptual framework of this program-project is that an interrelationship between the nervous system and endocrine system exists that is essentially a "two-way street"; age changes in the brain influence changes in the endocrine system and conversely, age changes in the endocrine system are equally important in producing age changes in the brain. Age changes in both integrating systems can occur and exert significant effects on peripheral aging. In this program-project, an animal model of chronic stress will be utilized and the cumulative effects of this mild chronic stress will be studied for up to 25 percent of the rat's lifespan in order to assess the role of stress on aging process. Chronic stress is employed to "provoke" the neuroendocrine system in order to determine the mechanisms by which the nervous and endocrine systems exert their effects on aging. This program-project will seriously and thoroughly test the hypothesis that stress influences aging and provide strong insights into hormonal mediating mechanisms. Correlations will be established between central nervous system morphology and function, neurochemical systhesis and transmission, autonomic nervous system reactivity and endocrine secretions during normal aging and during condition of increased physiological activity provoked by chronic stress. This project will provide strong insights into hormonal mediating mechanisms and will yield significant information on the factors that predispose to heightened susceptibility to stress-induced pathology during aging. The long-term goal is to establish the role of stress in aging and to develop interventions that utilize this information to modulate the aging process.